A Low-Energy High-Density Capacitor-Less I&F Neuron Circuit Using Feedback FET Co-Integrated With CMOS

Abstract

We have developed a capacitor-less I&F neuron circuit with a dual gate positive feedback fieldeffect transistor (FBFET) and successfully co-integrated FBFET and CMOS in a wafer. By implementing the neuron circuit with FBFET, we can overcome the limits of conventional CMOS, reduce energy consumption, and imitate the biological neuron. The floating body of the FBFET can replace the membrane capacitor that occupies a large area and performs leaky integration of the neuron. Due to the extremely low sub-threshold swing of the FBFET (less than 0.528mv/dc), energy consumption of the neuron is significantly reduced by suppressing sub-threshold current. Finally, we analyzed the fabricated neuron circuit operation, retention time of the integrated charges and energy consumption compare to conventional CMOS neuron circuit.INDEX TERMS Integrate-and-fire neuron circuit, positive feedback FET, low energy consumption, floating body effect.

Low-Power and High-Density Neuron Device for Simultaneous Processing of Excitatory and Inhibitory Signals in Neuromorphic Systems

“…If the Vh is lower than a certain potential (Vth in conventional LIF neuron), the PF device turns on due to the PF operation and the neuron circuit generates a spike. In addition, the depth of the potential well in the n region affects the time constant () of the retention time of the accumulated electrons, and VG3 can control the depth of the potential well [21,24]. As a result, the proposed neuron circuit based on the PF device plays a role of the conventional LIF neuron with functionality of adjusting the time constant.…”

“…Note that processing these signals simultaneously can reduce memory usage and simplify the peripheral circuitry. To alleviate these hardware burdens, memristor-based [14][15][16] and FET-based neuron devices [18][19][20][21][22][23] with memory functionalities have been studied to mimic neurons. Memristor-based neuron devices with two terminals replace membrane capacitors in neuron circuits and have the advantage of high density over membrane capacitor and FET-based neuronal devices.…”

“…In addition, memristor-based neuron devices require additional circuits such as a differential amplifier to compare the resistance of the memristor to a reference resistance and a circuit so as to reset the memristor after the integrate-andfire operation. On the other hand, FET-based neuron devices, capable of resolving these issues, can process signals from two types (G + and G -) of synapses sequentially or only one type of signals [18][19][20][21][22][23]. However, FET-based neuron devices processing only one type of signals are paired for excitatory and inhibitory signals, and require additional circuits for logic operation in the neural networks.…”

“…When the PF neuron device turns off, the electrons accumulated in the n region are reduced over time by recombination, which shows a leaky integration. The reduction is related to the retention time, which can be controlled by G3 over the long-term [21,24]. The Vh is modulated by VG3 as shown in Fig.…”

Investigation of Monolithic 3D Integrated Circuit Inverter with Feedback Field Effect Transistors Using TCAD Simulation

“…Therefore, it can be used as a logic and memory device with the same structure. Various applications of FBFET were studied, such as using it as a logic device, a memory device, and a neuron circuit [ 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. In the previous study, we investigated electrical coupling between vertically stacked FBFETs in the monolithic 3-dimensional inverter (M3DINV) with FBFETs, in terms of device characteristics [ 31 ].…”